The present disclosure is directed to a plunger type pump to be set in a well which produces high gravity oil, or alternatively oil which is laden with substantial quantities of sand. In circumstances of this sort, it is necessary to periodically pull the pump on the production string so that servicing can be implemented, one example being the washing of sand from the lower parts of the well. In another instance, it may be necessary to disconnect and later reconnect the plunger type pump for restarting production.
After a well has been completed and casing has been set, perforations are normally made into a formation of interest where the oil produces into the well. It typically produces in a zone above a bridge plug or other bottom packer, and a pump supported packer is installed near the production zone. A plunger type pump is normally installed on or connected with the packer which supports the pump. This permits the pump to be anchored or stationary in the cased hole. The pump is then connected with a production tubing string extending thereabove, and a string of sucker rods is connected through the production tubing to reciprocate the pump.
It is not uncommon to encounter an oil producing formation which yields a high gravity oil. It typically will have tar like consistency and is somewhat difficult to produce. Another factor which changes the handling of the oil is production of sand in the oil. Excessive sand can materially alter flow characteristics of the oil. In either case, the produced oil is difficult to handle because it is so viscous. Even at greater depths, depth sufficient to expose the oil to increased temperatures, the temperature is not necessarily high enough to convert the tacky fluid into a more viscous fluid. Even where some change in viscosity does occur, sand particles may settle out from the standing column of oil in the production tubing and clog the regions around the pump. As the sand collects in the pump, it is necessary to periodically disassemble the pump and clean out the sand particles.
The present apparatus is an improved, easily removed, plunger type pump which can be removed quite readily on the tubing string. It is constructed with an elongate pump cylinder which terminates at a valve body and that in turn is threaded on the exterior or tapered to enable stabbing into the supportive hold down or packer on which the pump apparatus is supported. A lower check valve is included in this assembly, and opens into the pump cylinder. The pump cylinder encloses the double acting plug supported on the polished tube for reciprocation. The polished tube passes through a double acting packoff bushing, and extends upwardly thereabove to an upper check valve assembly. The polished tube is hollow so that production oil which is admitted from the lower check valve is periodically forced into the polished tube and is raised in the polished tube. As the stroke is made, the polished tube will move downwardly, forcing production oil up through the polished tube and out through the upper check valve at the top end of the polished tube. This forces the production oil above the packoff bushing. In that region, it then forms a standing column of oil extending up through the pump cylinder top section, an appropriate set of breakout bushings, and then into a connective sub. This sub is threaded to the equipment just described and, at the top end, it joins to a J-slot pin mechanism which is adapted for joinder to the lower end of the production tubing. In addition, the upper check valve has a fitting at the top end which threads to a sucker rod breakout lug mechanism and then to a string of sucker rods. The breakout lugs match breakout slots thereabove on a bushing so that the sucker rod string can be pulled upwardly, positioning the breakout lugs in the bushing slots permitting disengagement of the sucker rod string at the bottom most threaded joint. This unthreading sequence is accomplished by threading, a direction which would otherwise tighten all threaded joints in the sucker rod string. J-slots are included in the topmost sub. The production tubing string and the top sub are joined by a sized shear pin which permits an upward pull to make disconnection. When the upward pull occurs, the tubing string is pulled upwardly by a short distance to initiate operation of the pin and J-slot mechanism. This assures complete disconnection of the tubing string. Complete disconnection of the sucker rod string is accomplished in the manner mentioned so that the entire plunger type pump mechanism is completely disconnected.